# Cyclodextrin-Based Systems of Cetraria islandica Extracts: A Novel Approach to Improve Solubility and Biological Activity of Lichen-Derived Natural Products

## TL;DR

This study explores using cyclodextrins to improve the solubility and biological activity of compounds from the lichen Cetraria islandica.

## Contribution

The first study to prepare and characterize cyclodextrin-based systems with Cetraria islandica extracts.

## Key findings

- HP-β-CD and HP-γ-CD systems via solvent evaporation showed higher biological activity and FPCA release.
- CD-based systems improved the physicochemical properties of lichen-derived compounds.
- XRPD and FTIR confirmed the successful formation of CD–extract complexes.

## Abstract

Cetraria islandica (L.) Ach. (CI) is a lichen from the Parmeliaceaea family used in medicine. However, the low solubility of CI secondary metabolites in water limits the application of lichen extract and compounds. It prompted us to study the systems of cyclodextrins (CDs) (β-CD, γ-CD, HP-β-CD, and HP-γ-CD) with the CI acetone or CI methanol extracts prepared using grinding and solvent evaporation methods. The content of fumarprotocetraric acid (FPCA), a key CI metabolite, was quantified using HPLC. CD–extract systems were characterized by X-ray powder diffraction (XRPD) and Fourier-transform infrared (FTIR) spectroscopy. Biological activity was evaluated using cell-free assays: a Folin–Ciocalteu analysis, DPPH test, acetylcholinesterase, butyrylcholinesterase, and tyrosinase inhibitions. Dissolution profiles were also assessed. The best biological and physicochemical results were obtained for systems prepared with HP-β-CD and HP-γ-CD via solvent evaporation, showing higher activity and enhanced FPCA release compared to the pure extracts. To the best of our knowledge, this is the first study to report the preparation and characterization of CD-based systems with CI extracts. The obtained results encourage us to continue our research on CI to improve the physicochemical properties of its active compounds.